Is there any way to reload Main page every time when user changes an option inside the Settings page?

I have a settings page where I can set the global variable (0-Metric , 1-Imperial)

I have main page that I need to reload and change text values everytime this variable is changed (from picker inside Settings page)

I tried OnAppearing() function. But the text stays the same. (Code works only once when starting app)

Code (AboutPage):

protected override void OnAppearing()
    {

        base.OnAppearing();

        int system = ((App)App.Current).system_global; //global varible changed from settings page
        test.Text = system.ToString(); //used for debug

        //Metric
        if (system == 0)
        {
            devide = 100;

            Label_distance.Text = "Distance travelled (km):";
        }

        //Imperial
        else if (system == 1)
        {
            devide = 1;

            Label_distance.Text = "Distance travelled (miles):";
    }

Code (Settings page):

private void Picker_SelectedIndexChanged(object sender, EventArgs e)
    {
        system = Picker_Settings.SelectedIndex; //change global variable to 0 or 1
        test.Text = "Update:" + system.ToString(); //debug
    }

Is there any way to reload AboutPage every time when user changes an option inside the picker?